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POOpenCV compare two images and get different pixels
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copied!<p>For some reason the code bellow is not working. I have two 640*480 images which are very similar but not the same (at least few hundred/thousand pixels should be different).</p> <p>This is how I am comparing them and counting different pixels:</p> <pre><code>unsigned char* row; unsigned char* row2; int count = 0; // this happens in a loop // fIplImageHeader is current image // lastFIplImageHeader is image from previous iteration if ( NULL != lastFIplImageHeader->imageData ) { for( int y = 0; y < fIplImageHeader->height; y++ ) { row = &CV_IMAGE_ELEM( fIplImageHeader, unsigned char, y, 0 ); row2 = &CV_IMAGE_ELEM( lastFIplImageHeader, unsigned char, y, 0 ); for( int x = 0; x < fIplImageHeader->width*fIplImageHeader->nChannels; x += fIplImageHeader->nChannels ) { if(row[x] != row2[x] || row[x+1] != row2[x+1] || row[x+2] != row2[x+2]) count++; } } } } </code></pre> <p>Now at the end I get number 3626 which would seem alright.</p> <p>But, I tried opening one of the images in MS Paint and drawing thick red lines all over it which should increase the number of different pixels substantially. I got the same number again: 3626.</p> <p>Obviously I am doing something wrong here.</p> <p>I am comparing these images in a loop.</p> <p>This line is before the loop:</p> <pre><code>IplImage* lastFIplImageHeader = cvCreateImageHeader(cvSize(640, 480), 8, 3); </code></pre> <p>Then inside the loop I load images like this:</p> <pre><code>IplImage* fIplImageHeader = cvLoadImage( filePath.c_str() ); // here I compare the pixels (the first code snippet) lastFIplImageHeader->imageData = fIplImageHeader->imageData; </code></pre> <p>So lastFIplImageHeader is storing the image from the previous iteration and fIplImageHeader is storing the current image.</p>

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